Subject: Re: CCL:G:G:Gaussian on a Mac ? ---Or Other Platforms

From: [email-masked] (Mike Frisch)
Date: Fri, 11 Jul 1997 10:08:16 -0400 (EDT)

M. Nicklaus writes:
> 
> Hi,
> 
> On Thu, 10 Jul 97, "Frederick R. Bennett" <[email-masked] wrote:
> 
> >  I know that Gaussian Inc. hates this sort of thing but I will ask anyway. I
> > am wondering whether anyone has G94 running on a PowerMac running one of the
> > Linux operating systems (MKLinux or the non-Micro Kernal).
> > 
> >  Just as a matter of opinion, I think that Gaussian Inc. should seriously
> > consider supporting this platform, as they do the various Unices running on
> > Intel machines. The motorola PowerPC chips are leaving Intel Pentiums for
> > dead at the moment and with the new generation motorola chips on the way
> > out, fast system buses and new cacheing technology, Mac's or Mac clones
> > should/can provide the hardware for some high power/cost ratio workstations
> > for chemistry.
> 
> Since this can has been opened, let me chip in with a remark and a question.
> 
> 1. I agree with Frederick R. Bennett in that Gaussian Inc. should support
> more of the new fast, and *cheap*, platforms such as PowerPC systems 
> running Linux.  I'd like to expand this request to include Alpha CPU systems
> running axp Linux.  These chips are even faster than the PowerPC's.  We've
> benchmarked them with other software.  500 MHz machines (non-DEC) can be had 
> for $5,000-6,000.  The 600 MHz 21164 chip based systems are basically shipping 
> (albeit expensive, ~$11k), and the 800 MHz CPUs are in the pipeline.
> 

We at Gaussian, Inc. agree with this, but in practice it requires a reliable
operating system, and this is definately not the case for Linux/Alpha, and
is questionable for Linux/PPC.

> 2. We've tried to compile G94, Rev. E.1 for such a 21164 500 MHz Alpha based
> system, running RedHat Linux 4.1, kernel v. 2.0.27 --- unfortunately, 
> unsuccessfully so far.  We've experienced problems with f2c, gcc, as well as
> the linker.  So therefore my question: Has anyone been able to get G94 to
> run on this platform?  If yes, how?
> 

We have an Alphax/Linux machine in house but Linux for Alpha has turned out
to be very, very far from the stable environment Linux is for Intel machines.
For example, there are well-documented and very serious problems linking
large programs which have not yet been resolved.  Anyone interested can
subscribe to the Linux/Alpha mailing list and receive a dozen or so examples
PER DAY of things that work under Linux/Intel but not under Linux/Alpha.  

When Linux is actually stable for production use on processors other than
Intel, we certainly intend to support Gaussian there.

Mike Frisch
Gaussian, Inc.

---

From: Rick Venable <[email-masked]>
Date: Sun, 13 Jul 1997 13:54:39 -0400 (EDT)

> is questionable for Linux/PPC.

I can independently confirm that state of affairs; while Linux on Intel is
a viable marketplace with a good Fortran compiler from AbSoft, both
LinuxAXP (Alpha chip) and MkLinux (PPC chip) have serious efficiency
problems, as well as being a bit buggy.  LinuxAXP is a bit further along,
with companies like MicroWay helping the effort, while Apple seems to be
backing away from MkLinux.  As a consequence, there's renewed effort for
LinuxPPC (uses standard Linux kernel vs. Mach kernel for MkLinux). 

The real problem is g77, at least for compute intensive scientific
applications; compared to the same code compiled under the vendor's OS,
Linux g77 apps seem to be 3-5 times slower under LinuxAXP, and 8-10 times
slower under MkLinux.  Because of the large Intel base and the relatively
low usage of LinuxAXP (vs. DEC Unix or MS WinNT) and MkLinux/LinuxPPC (vs. 
MacOS), it's not clear there will be a good commercial Fortran compiler
anytime soon for either LinuxAXP or the PPC versions.  An alternative
would be an overhaul of the PPC and/or Alpha specific portions of g77 by a
gifted volunteer with a knowledge of compiler design and RISC floating
point architectures. 

[ Note: this not a criticism of g77 in general, and I think Mr. Burley has
done an admirable job in providing it.  While it is amazing that g77 works
on so many different machines, it isn't surprising that the resulting code
doesn't always provide comparable performance. ]

Based on my own experiences with MkLinux and detailed perusal of both
LinuxAXP and MkLinux FAQ lists and mailing list archives, I certainly
would not criticize any software vendor who takes a "wait and see" 
attitude towards these variants of Linux.  It is especially true if a good
Fortran compiler is a requirement. 

--
Rick Venable                  =====\     |=|    "Eschew Obfuscation"
FDA/CBER Biophysics Lab       |____/     |=|
Bethesda, MD  U.S.A.          |   \    / |=|  ( Not an official statement or
[email-masked]  |    \  /  |=|    position of the FDA; for that,
http://nmr1.cber.nih.gov/           \/   |=|    see   http://www.fda.gov  )